<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>flex布局案例1</title>
</head>

<body>
    <div class="box">
        <div id="one"></div>
        <div id="two">
            <div id="frist"></div>
            <div id="second"></div>
            <div id="thrid"></div>
        </div>
        <div id="three"></div>
    </div>
    <style>
        .box {
            background-color: aqua;
            height: 100%;
            display: flex;
            flex-direction: column;
        }

        body,
        html {

            height: 100%;
        }

        #one {
            height: 100px;
            background-color: cornflowerblue;
        }

        #two {
            flex: auto;
            display: flex;
            flex-direction: row;
        }

        #three {
            background-color: cornflowerblue;
            height: 100px;
        }

        #frist {
            flex-basis: 100px;
            background-color: darkgrey;
        }

        #second {
            flex: auto;
        }

        #thrid {
            flex-basis: 100px;
            background-color: darkgray;
        }
    </style>
</body>

</html>